Sorry to upvote a pedantic comment, but the instrument here is definitely not a wood or kelon xylophone, and is instead a glockenspiel. The solenoid striking scheme would probably need to be slightly different for a xylophone, to avoid wear on the more delicate keys. A softer, rounded tip, needing more clearance beneath, would probably be required. Marimbas and vibraphones would require even softer strikes as well. Really great project!